In the last two decades, powdery mildew resistance has been investigated in a large number of barleys grown in the Czech Republic. However, only 14 winter barley cultivars were resistant to all used isolates. In this paper, new tests on these cultivars and also on ‘Verena’ are presented. Thirty-two reference isolates of Blumeria graminis f. sp. hordei, including some isolates collected in 2009, were used. One of the latter was virulent on ‘Laverda’ and ten other six-rowed cultivars. It is recommended that this resistance be designated Lv. Another six-rowed cultivar ‘Dubai’ showed a different resistance to which virulent isolates were also found in 2009. Thus, four resistances were found among the 15 cultivars and only three two-rowed cultivars ‘Himalaya’, ‘Venezia’ and Br4190a1 showing two different resistance spectra remain fully resistant to all used isolates.
Spring barley was the second largest crop in Slovakia. Resistance genes in cultivars registered in Slovakia from 2000 to 2010 were identified using the postulation method. Forty-three cultivars including 30 individually harvested plants, two parents ‘Meltan’ and ‘Pax’ and a standard line SK5968 were tested at the seedling stage for their reaction to 40 selected isolates of Blumeria graminis f. sp. hordei. In total, 19 resistance spectra were detected and the following 13 resistance genes were postulated, namely mlo, Mla1, Mla6, Mla12, Mla13, MlaRu4, Mlat, Mlg, MlLa, Ml(Ab), Ml(Hu4), Ml(Ro) and Ml(St). Two unknown resistances were detected in ‘Calcule’ and ‘Spilka’. Two cultivars (‘Madonna’ and ‘Nadir’) exhibited heterogeneity for mildew resistance. The most frequent gene was mlo, which was present in 25 of the tested cultivars. Some new results to previously published data were found.
In PI466495, a powdery mildew resistance source of wild barley (
), one gene conferring powdery mildew resistance was identified in the
locus. In this paper, the
gene sequence was used as source for the development of a cleaved amplified polymorphic sequence (CAPS) marker. Co-segregation between this marker and powdery mildew resistance was analysed by specific DNA fragments associated with each allele of the gene using 286 F
plants derived from a cross between winter barley (
L.) variety ‘Tiffany’ and PI466495. For the co-dominant marker
, three fragments, 370 bp, 82 bp and 59 bp in size, were amplified from F
plants exhibiting resistance reaction types 0 and 0–1 to powdery mildew; whereas two fragments, 429 bp and 82 bp in size, were amplified in susceptible plants. Simple procedures based on polymerase chain reaction and restriction enzyme digestion allowed for identifying the plants susceptible to powdery mildew (
) and plants homozygous or heterozygous for the resistance allele. The
marker was positioned 0.85 cM to the resistance gene and the efficiency of marker-assisted selection (MAS), evaluated as the probability of crossing-over between the marker and the targeted gene, was 99%. The CAPS marker
is a valuable candidate for MAS and gene transfer into barley varieties susceptible to powdery mildew.
Thirteen accessions of wild barley (
) resistant to powdery mildew caused by the fungus
were studied with the aim of determining the number of resistance genes and their allelic relationships to the
locus on the short arm of chromosome 1H. In five accessions (PI391130, PI466193, PI466200, PI466495 and PI466510), the resistance was caused by one gene, in seven accessions (PI354949, PI391081, PI466158, PI466197, PI466211, PI466297 and PI466461) by two independent genes and in PI301004 by three independent genes. The type of inheritance of all analysed genes except two was dominant or semi-dominant; only one of two genes in PI391081 and PI466297 was recessive. Allelism tests confirmed that in 10 accessions one gene was allelic with the
locus, and in three accessions (PI391081, PI466193 and PI466297) the resistance genes were different from the